[RFC PATCH 1/2] xen/arm: Add Amlogic S905 SoC early printk support

[Amit Singh Tomar <amittomer25@gmail.com>]

Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
---
 docs/misc/arm/early-printk.txt     |  1 +
 xen/arch/arm/Rules.mk              |  1 +
 xen/arch/arm/arm64/debug-meson.inc | 50 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)
 create mode 100644 xen/arch/arm/arm64/debug-meson.inc

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index f765f59..2aa9528 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -41,6 +41,7 @@ the name of the machine:
   - juno: printk with pl011 on Juno platform
   - lager: printk with SCIF0 on Renesas R-Car H2 processors
   - midway: printk with the pl011 on Calxeda Midway processors
+  - meson: printk with the MESON for Amlogic S905 SoCs
   - mvebu: printk with the MVEBU for Marvell Armada 3700 SoCs
   - omap5432: printk with UART3 on TI OMAP5432 processors
   - rcar3: printk with SCIF2 on Renesas R-Car Gen3 processors
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index f264592..d4fabdc 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -36,6 +36,7 @@ EARLY_PRINTK_hikey960       := pl011,0xfff32000
 EARLY_PRINTK_juno           := pl011,0x7ff80000
 EARLY_PRINTK_lager          := scif,0xe6e60000
 EARLY_PRINTK_midway         := pl011,0xfff36000
+EARLY_PRINTK_meson          := meson,0xc81004c0
 EARLY_PRINTK_mvebu          := mvebu,0xd0012000
 EARLY_PRINTK_omap5432       := 8250,0x48020000,2
 EARLY_PRINTK_rcar3          := scif,0xe6e88000
diff --git a/xen/arch/arm/arm64/debug-meson.inc b/xen/arch/arm/arm64/debug-meson.inc
new file mode 100644
index 0000000..d5507d3
--- /dev/null
+++ b/xen/arch/arm/arm64/debug-meson.inc
@@ -0,0 +1,50 @@
+/*
+ * xen/arch/arm/arm64/debug-meson.inc
+ *
+ * MESON specific debug code.
+ *
+ * Copyright (c) 2018, Amit Singh Tomar <amittomer25@gmail.com>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#define UART_STATUS_REG     0x0c
+#define UART_TX_REG         0x00
+
+/*
+ * MESON UART wait UART to be ready to transmit
+ * xb: register which contains the UART base address
+ * c: scratch register
+ */
+.macro early_uart_ready xb c
+1:
+        ldrh   w\c, [\xb, #UART_STATUS_REG] /* status register */
+        tst    w\c, #(1 << 21)              /* Check TXFIFO FULL bit */
+        b.ne   1b                           /* Wait for the UART to be ready */
+.endm
+
+/*
+ * MESON UART transmit character
+ * xb: register which contains the UART base address
+ * wt: register which contains the character to transmit
+ */
+.macro early_uart_transmit xb wt
+	strb  \wt, [\xb, #UART_TX_REG]
+.endm
+
+/*
+ * Local variables:
+ * mode: ASM
+ * indent-tabs-mode: nil
+ * End:
+ */
-- 
1.9.1


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